Musculocutaneous nerve

Assoc Prof Craig Hacking ◉ ◈ and Dr Henry Knipe ◉ ◈ et al.

The musculocutaneous nerve is one of five major branches of the brachial plexus and supplies motor innervation to the arm and sensory innervation to the forearm.

Gross anatomy

Origin

The musculocutaneous nerve is one of two terminal branches of the lateral cord of the brachial plexus (along with the lateral root of the median nerve). It receives fibers from the C5-7 nerve roots.

Course

In the axilla, the musculocutaneous nerve courses laterally away from the axillary artery, pierces (and supplies) the coracobrachialis muscle and descends towards the elbow between biceps brachii and brachialis muscles.

In the cubital fossa, it courses lateral to the biceps tendon as the lateral cutaneous nerve of the forearm, which is simply the sensory continuation of the musculocutaneous nerve after it has distributed all its motor fibers in the anterior compartment of the arm.

Branches and supply

muscular branches: anterior compartment of the arm (coracobrachialis, biceps brachii and brachialis muscles)
articular branches: shoulder and elbow joints
lateral cutaneous: lateral aspect of the forearm

Anatomical Variants

coursing behind coracobrachialis ²
may transmit fibers to/from median nerve ²
supply of pronator teres ²

Quiz questions

References

Anatomy: Upper limb

Anatomy: Upper limb

skeleton of the upper limb
- clavicle
  - conoid tubercle
  - supraclavicular foramen
- scapula
- humerus
  - supracondylar spur
  - olecranon foramen
- radius
- ulna
- carpal bones (mnemonic)
  - scaphoid
    - bipartite scaphoid
  - lunate
    - lunate morphology
  - triquetrum
  - pisiform
  - trapezium
  - trapezoid
  - capitate
  - hamate
  - variants
    - carpal coalition
      - lunotriquetral coalition
      - capito-hamate coalition
- metacarpals
- phalanges
  - terminal tuft
- accessory ossicles of the upper limb
  - accessory ossicles of the shoulder
    - os acromiale
  - accessory ossicles of the elbow
    - os supratrochleare dorsale
    - patella cubiti
  - accessory ossicles of the wrist (mnemonic)
    - os centrale carpi
    - os epilunate
    - os styloideum
    - os hamuli proprium
    - lunula
    - os triangulare
    - trapezium secondarium
    - os paratrapezium
    - os radiostyloideum (persistent radial styloid)
joints of the upper limb
- shoulder joint
  - articulations
  - associated structures
    - joint capsule
    - bursae
      - subacromial-subdeltoid (SASD) bursa
      - subscapular recess
      - subcoracoid bursa
      - coracoclavicular bursa
      - supra-acromial bursa
    - ligaments
      - coracoclavicular ligament
        
        conoid ligament
        
        trapezoid ligament
      - costoclavicular ligament
  - movements
    - scapulothoracic joint
      - scapular retraction (adduction)
      - scapular protraction (abduction)
      - scapular elevation
      - scapular depression
      - scapular lateral rotation
      - scapular medial rotation
    - glenohumeral joint
      - arm flexion
      - arm extension
      - arm abduction
      - arm adduction
      - arm internal rotation (medial rotation)
      - arm external rotation (lateral rotation)
      - circumduction
  - blood supply - scapular anastomosis
  - ossification centers
- elbow joint
  - proximal radioulnar joint
  - ligaments
    - medial (ulna) collateral ligament complex
    - lateral (radial) collateral ligament complex
  - associated structures
    - bicipitoradial bursa
    - olecranon bursa
  - movements
  - alignment
  - blood supply - elbow anastomosis
  - development
    - elbow ossification (mnemonic)
    - elbow ossification centers
- wrist joint
  - articulations
  - ligaments
    - intrinsic ligaments
    - extrinsic ligaments
  - associated structures
    - extensor retinaculum
    - flexor retinaculum
    - joint capsule
  - movements
  - alignment
    - carpal arcs
  - ossification
- hand joints
  - articulations
    - carpometacarpal joint
      - triscaphe joint
    - metacarpophalangeal joint
      - palmar ligament (plate)
      - collateral ligament
    - interphalangeal joint
      - palmar ligament (plate)
      - collateral ligament
  - movements
spaces of the upper limb
muscles of the upper limb
blood supply to the upper limb
- arteries
- veins
innervation of the upper limb
- intercostobrachial nerve
- brachial plexus (mnemonic)
  - branches from the roots
  - branches from the trunks
    - suprascapular nerve
  - branches from the cords
    - lateral cord
      - lateral pectoral nerve
    - posterior cord
    - medial cord
  - terminal branches
    - ulnar nerve
    - radial nerve
      - posterior interosseous nerve (deep radial nerve)
      - superficial radial nerve
    - musculocutaneous nerve
    - axillary nerve
    - median nerve
      - anterior interosseous nerve
      - bifid median nerve
lymphatic drainage of the upper limb
- axillary lymph nodes

Article information

rID: 24693

System: Musculoskeletal

Section: Anatomy

Tag: cases, refs, cases, nerve, cases

Synonyms or Alternate Spellings:

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Cases and figures

Figure 1: musculocutaneous nerve Figure 1: musculocutaneous nerve

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Figure 2: labeled brachial plexus Figure 2: labeled brachial plexus

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